The present invention relates to froth flotation of minerals.
Froth flotation is used for dressing or beneficiating ore at or near the mine site to produce one or more concentrates of valuable minerals. Particles of the ore are suspended in water in the presence of a collector chemical which renders the mineral particles air-avid and water-repellent. The ore particles are subjected to agitation and aeration and the mineral particles which are treated with the collector rise to the top of the vessel and become concentrated there in a froth or foam. In most cases, it is the desired mineral which rises to the top for collection as product. In some cases, however, the undesired minerals rise to the surface and the desired mineral is removed with water from the bottom of the vessel. An example of the latter system is glass-sand flotation where iron-bearing minerals are separated as froth and high grade silica values are removed from the bottom of the flotation vessel.
While froth flotation is by far the dominant process of mineral dressing in present use, there have been many attempts to improve the process, particularly in achieving more efficient or sharper separation. In particular, there have been developed many modifiers which, when added to the flotation systems, increase the selectivity of the collector for the mineral desired to be floated. This type of modifier is frequently referred to as a depressant. Examples of known depressants include quebracho, tannin or acidified sodium dichromate to depress calciferous minerals. With many ores, however, these depressants are not particularly successful in depressing troublesome gangue materials.
It is an object of the present invention to provide an improved method of froth flotation. It is a further object to provide an improved method of mineral concentration by froth flotation. It is a further object to provide an improved depressant for use in mineral froth flotation and it is a further object to provide an improved method of scheelite flotation using a novel depressant in conjunction with a conventional collector material.